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151.
152.
Silva Patrícia F. N. Alfieri Alice F. Barry Aline F. de Arruda Leme Raquel Gardinali Noemi R. van der Poel Wim H. M. Alfieri Amauri Alcindo 《Tropical animal health and production》2015,47(1):237-241
Tropical Animal Health and Production - Norovirus (NoV) is a member of the Caliciviridae family and is considered an emerging human enteric pathogen. NoVs are detected in farm animals such as... 相似文献
153.
In coastal foredunes, the grass Ammophila arenaria develops a soil community that contributes to die-back and replacement by later successional plant species. Root-feeding nematodes and pathogenic soil microorganisms are involved in this negative feedback. Regular burial by wind-blown beach sand results in vigorous growth of A. arenaria, probably because of enabling a temporary escape from negative soil feedback. Here, we examine the role of root-feeding nematodes as compared to the whole soil community in causing negative feedback to A. arenaria. We performed a 3-year sand burial experiment in the field and every year we determined the feedback of different soil communities to plant growth in growth chamber bioassays.In the field, we established A. arenaria in tubes with beach sand, added three endoparasitic root-feeding nematode species (Meloidogyne maritima, Heterodera arenaria and Pratylenchus penetrans) or root zone soil to the plants, and created series of ceased and continued sand burial. During three subsequent years, plant biomass was measured and numbers of nematodes were counted. Every year, bioassays were performed with the field soils and biomass of seed-grown A. arenaria plants was measured to determine the strength of feedback of the established soil communities to the plant.In the field, addition of root zone soil had a negative effect on biomass of buried plants. In the bioassays, addition of root zone soil also reduced the biomass of newly planted seedlings, however, only in the case when the field plants had not been buried with beach sand. Addition of the three endoparasitic root-feeding nematodes did not influence plant biomass in the field and in the bioassays. Our results strongly suggest that the negative feedback to A. arenaria is not due to the combination of the three endoparasitic nematodes, but to other components in the soil community, or their interactions with the nematodes. 相似文献
154.
Johan?VermeulenEmail author Tim?Grotenhuis Jan?Joziasse Wim?Rulkens 《Journal of Soils and Sediments》2003,3(1):49-59
Background and Goal In the Netherlands about 40 million m3 of sediment has to be dredged annually for both maintenance and environmental reasons. Temporary upland disposal is the most
widely adopted alternative for dredged sediments worldwide. For good management of temporary disposal sites, knowledge is
needed on the processes controlling the behavior of the sediments during disposal. Therefore, a review of the literature was
made to get an integrated overview about processes that take place during temporary disposal.
Ripening After disposal of clayey sediments, the following spontaneous dewatering processes can be distinguished: sedimentation, consolidation,
and ripening. Sedimentation and consolidation are relatively fast processes, whereas ripening can take up to several years.
In a remediation perspective, the ripening of sediments is the most important dewatering process. Ripening, which may be subdivided
into physical, chemical, and biological ripening, transforms sediment into soil. Physical ripening is the irteversible toss
of water and results in the formation of soil prisms separated by shrinkage cracks. Continuing water loss causes a breaking
up of the prisms into aggregates. The aggregates produced by this ongoing desiccation process usually remain quite large (>50
mm) and can only be further broken down by weathering processes like wetting and drying or by tillage. As a result of the
aeration caused by physical ripening, also chemical and biological ripening take place. Chemical ripening can be defined as
the changes in chemical composition due to oxidation reactions and leaching of soluble substances. Biological ripening is
the result of the activity of all kinds of soil fauna and flora that develop as a result of aeration, including both the larger
and the microscopic forms of life. Decomposition and mineralization of soil organic matter caused by micro-organisms can be
seen as the most important aspect of biological ripening. Many interactions exist between the different ripening processes.
Conclusions and Outlook Oxygenation of the dredged sediment is improved as a result of the natural ripening processes: the air-filled porosity increases,
the aggregate size decreases, and the initially high respiration rates caused by chemical and biological ripening decreases.
Therefore, conditions in the disposal site become more favorable for aerobic biodegradation of organic pollutants like Polycyclic
Aromatic Hydrocarbons (PAH) and mineral oil. It is concluded that the naturally occurring process of ripening can be used
as a bioremediation technique. Ripening in an upland disposal site is an off-site technique, and therefore, the process could
be enhanced by means of technological interference. However, it is concluded that the knowledge currently available about
upland disposal is not sufficient to distinguish critical process steps during the ripening and bioremediation of PAH and
mineral oil polluted sediments because of the complex relationships between the different ripening processes and bioremediation. 相似文献
155.
Jouzel J Petit JR Souchez R Barkov NI Lipenkov VY Raynaud D Stievenard M Vassiliev NI Verbeke V Vimeux F 《Science (New York, N.Y.)》1999,286(5447):2138-2141
Isotope studies show that the Vostok ice core consists of ice refrozen from Lake Vostok water, from 3539 meters below the surface of the Antarctic ice sheet to its bottom at about 3750 meters. Additional evidence comes from the total gas content, crystal size, and electrical conductivity of the ice. The Vostok site is a likely place for water freezing at the lake-ice interface, because this interface occurs at a higher level here than anywhere else above the lake. Isotopic data suggest that subglacial Lake Vostok is an open system with an efficient circulation of water that was formed during periods that were slightly warmer than those of the past 420,000 years. Lake ice recovered by deep drilling is of interest for preliminary investigations of lake chemistry and bedrock properties and for the search for indigenous lake microorganisms. This latter aspect is of potential importance for the exploration of icy planets and moons. 相似文献
156.
157.
158.
Ecological linkages between aboveground and belowground biota 总被引:12,自引:0,他引:12
Wardle DA Bardgett RD Klironomos JN Setälä H van der Putten WH Wall DH 《Science (New York, N.Y.)》2004,304(5677):1629-1633
All terrestrial ecosystems consist of aboveground and belowground components that interact to influence community- and ecosystem-level processes and properties. Here we show how these components are closely interlinked at the community level, reinforced by a greater degree of specificity between plants and soil organisms than has been previously supposed. As such, aboveground and belowground communities can be powerful mutual drivers, with both positive and negative feedbacks. A combined aboveground-belowground approach to community and ecosystem ecology is enhancing our understanding of the regulation and functional significance of biodiversity and of the environmental impacts of human-induced global change phenomena. 相似文献
159.
Toward the realization of nanoscale device control, we report a molecular valve embedded in a membrane that can be opened by illumination with long-wavelength ultraviolet (366 nanometers) light and then resealed by visible irradiation. The valve consists of a channel protein, the mechanosensitive channel of large conductance (MscL) from Escherichia coli, modified by attachment of synthetic compounds that undergo light-induced charge separation to reversibly open and close a 3-nanometer pore. The system is compatible with a classical encapsulation system, the liposome, and external photochemical control over transport through the channel is achieved. 相似文献
160.
Mansonia Pulido Moncada Donald Gabriels Wim Cornelis Deyanira Lobo 《Land Degradation \u0026amp; Development》2015,26(8):843-852
Although there is not a sole satisfactory methodology that applies universally up to now, aggregate stability has been proposed as an indicator of soil physical quality (SPQ). Difficulties persist when comparison of aggregate stability from different procedures are performed. The objective of this study is to evaluate appropriate aggregate stability methods that enable to distinguish the SPQ condition of both temperate and tropical medium‐textured soils. Among different methods tested, results show that wet sieving using the well known fast wetting methods of Kemper & Rosenau and of Le Bissonnais rendered similar results in both environments. The mean weight diameter value of both methods for assessing aggregate stability can be considered as a dependable indicator of soil structure status for comparing soils. These aggregate stability methods are in correspondence with only one out of the eight SPQ indicators when entirely soils were used. It was concluded that the aggregate stability should be used judiciously and in concert with other indicators for an overall assessing of the SPQ condition. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献